MATH SOLVE

2 months ago

Q:
# A motorboat covers the distance from one pier to the other pier in 4 hours and the way back in 5 hours. What is the speed of the boat in still water, if it covers 70 km with the current in 3.5 hours?PLZ SHOW WORK AND DO NOT ESTIMATE

Accepted Solution

A:

speed of current ------ y km/h

distance with the current = 4(x+y)

distance against the current = 5(x-y)

we know that 3.5(x+y) = 70

x+y = 20

but 4(x+y) = 4(20) = 80

then 5(x-y) = 80

x-y = 16

x+y=20

x-y=16

add them

2x = 36

x = 18 , then y = 2

distance with the current = 4(x+y)

distance against the current = 5(x-y)

we know that 3.5(x+y) = 70

x+y = 20

but 4(x+y) = 4(20) = 80

then 5(x-y) = 80

x-y = 16

x+y=20

x-y=16

add them

2x = 36

x = 18 , then y = 2